In reading more about how freaking fantastic nutritional ketosis is for you, it's clear that fats are really good. There's some disagreement in which fats are better for you, though, so I did some digging.
Specifically, I wasn't sure if purified medium chain triglycerides (MCT) like those found in MCT oil or Brain Octane (100% 8 carbon chain fatty acids, also called Caprylic or octanoic acid) were better than the naturally occurring balance of 9% caprylic acid, 10% decanoic acid (10C fatty acids), 52% lauric acid (12C), and ~38% longer chains (14C, 16C, and 18C).
I'd initially read the bulletproof coffee guy, Dave Asprey, on why pure caprylic acid (the stuff he sells as "brain octane") was better:
ie: lauric acid (12C) is cheap and bad, so buy my refined Brain Octane with all the lauric acid taken out.
But wikipedia says:
So that doesn't quite line up, Mr. Asprey.
Wikipedia also says lauric acid is probably good for you:
The question here is really "is lauric acid good for you" and I think the answer is definitely yes.
However, lauric acid probably doesn't result in as much of a blood ketone boost as C10 MCT:
So if you're trying to boost blood ketone levels, pure C8 will probably be more effective than coconut oil. I think this means that it's metabolized more effectively.
I think it's also clear that LCTs (16-18C found in vegetable or seed oils) are probably worse for you than MCTs (8-10C):
My general philosophy in nutrition is to start with the assumption that I don't know anything, and nobody else does either. All of this data doesn't prove anything one way or another, we just get hints of what's probably better or worse for us in the long run.
To that end, based on the limited information I have, I think it's safe to say that regular coconut oil is super good for you, and that purified MCT oil is probably a fad but does help in raising blood ketone levels and therefore probably short term energy levels. If I had to pick one, I'd wager you'd get more long-term benefit from consuming just coconut oil than just MCT oil.